Field of the Invention
The invention relates to a method of characterizing a signal, and more particularly to a method of detecting failures by using the characterization of a signal. The invention also relates to devices for performing such methods.
Description of the Related Art
Methods for detecting failures are known. In a first step A, a signal is acquired, e.g. a signal from a sensor. Thereafter, in subsequent steps, the signal is analyzed using a failure by failure method, i.e. each type of failure is identified one by one as a function of particular characteristics of the signal. For example, a flat signal is associated with a broken cable, a saturated signal with a sensor failure, etc. Those methods are generally cumbersome to implement because of the number of failures that need to be envisaged and the complexity of the intermediate analysis operations.
In order to remedy that drawback, certain manufacturers have developed failure detection methods that are optimized for their sensors and systems. Nevertheless, that solution is not satisfactory insofar as it depends on the sensor or the computer system used. In a complex system, in which a plurality of subsystems from different manufacturers co-exist, the use of a different failure detection method for each subsystem makes controlling the system as a whole considerably more cumbersome, and it is found to be a handicap whenever it is necessary to replace a component with an equivalent component from another manufacturer.
In addition, at the risk of degrading analyses or misleading an operator, it is important to avoid detecting failures that do not exist. Indeed, false detections can have consequences that are disastrous, e.g. when the controlled system is a space vehicle. In a space vehicle, such as a rocket engine, an erroneous detection of a failure can lead to overconsumption of propellant or to performing a command that is inappropriate for the real state of the system. Thus, when the method detects a failure, it must be possible to associate that failure detection with validity information indicating whether the failure detection is or is not reliable, and it must be possible to do so in a manner that is simple and robust.